Last week Jeff Bezos' space company demonstrated the first launch and return of Blue Origin's reusable rocket-powered stage. This unmanned "New Shepard" rocket lifted off from a west Texas test and launch facility, then returned and safely landed. This event is being lauded as a coup for space flight.

Media reports and quotes by Bezos go on to claim "Rockets have always been expendable. Not anymore," which appeared in a blog post on Blue Origin's website. This is a very exciting time for commercial space flight enthusiasts.

In fact, the search for a reusable rocket precedes Bezos' efforts by several decades. We have had access to the needed technologies for almost as long. The underlying deterring factor has not been a lack of capability, but a lack of affordability. There have been many government-funded and private-sector launcher programs in pursuit of reusability, but none have yet succeeded.

To date, all have tried to justify the investment needed for a successful reusable launch system. However, in every recent case there was insufficient market demand to drive the per-flight cost down to a level of affordability that could attract widespread demand for space travel. Most recently, several entrepreneurial companies have been developing reusable one- and two-stage launch systems that penetrate the atmosphere and offer a few minutes of weightless space exposure before returning to Earth. Blue Origin is one of those companies.

To be clear, such systems do not offer true space flight, but simply a taste of space. For true space flight one needs to escape the atmosphere and reach a speed of at least 17,000 miles per hour. Simply put, suborbital flights require an energy equivalent of about 4,000 miles per hour. This is less than a quarter of the energy needed to achieve true space flight. Clearly, we still have a long way to go to achieve affordable reusable space flight.

Furthermore, it is worth noting that the concept of vertical take-off and landing (VTOL) is not new. In the 1990s, the Delta Clipper Experimental (DC-X) was flown as an unmanned prototype of a reusable single-stage-to-orbit (SSTO) launch vehicle built by McDonnell Douglas. This was funded by the government from 1991 to 1996. However, the program ended when government funding ended. The private sector was not convinced the program would be a successful venture.

In the 1990s, Walter Kistler created a company that aspired to build and fly a commercial reusable two-stage-to-orbit (TSTO) rocket system that proposed vertically launching and landing of both stages. Unfortunately, Kistler could not attract enough funding to complete the first flight vehicle.

Nevertheless, it appears that regular commercial suborbital flights will likely be departing from several spaceports sometime in the near future. Some of these will use horizontal take-off and landing techniques, and others may use VTOL operational methods.